1. Field of the Invention
The invention relates to an improved boiler system utilizing solar radiation as its sole heat source. More particularly, the invention relates to a solar energy boiler having a preheat and steam pressure tank arrangement to maintain a predetermined water level in boiler tubes, in combination with solar energy collection means to maximize solar energy collection by focusing solar radiation and by continually directing the energy collecting surface normal to the direction of incidence of solar radiation throughout the day, with compensation for seasonal variations in the sun's position.
2. Description of the Prior Art
Many devices for collection of solar energy are known. Severy in U.S. Pat. No. 937,013 discloses a lens device associated with a solar tracking boiler to produce steam. The Severy device, however, requires manual adjustment of declination and winding of a coil spring for tracking diurnal solar motion.
Courtis et al in U.S. Pat. No. 2,182,222 show a parabolic reflector focusing solar energy on a boiler. However, a complex control mechanism is required due to a coordinate system not based upon apparent motion through the plane of the ecliptic.
Also showing focusing of solar radiation with a parabolic mirror rotated about its focus is the Ketchum U.S. Pat. No. 784,005, showing a vaporizer, motor, and reservoir or tank receiving heated liquid. Ketchum fails to disclose specifically the mechanism for movement of the mirror, and the apparatus suffers from problems characterizing all parabolic mirror reflectors, namely, reradiation from the absorber back to the enveloping surface of the mirror with consequent loss of collection efficiency. Other problems associated with a parabolic mirror also exist, such as requirement for providing special protection against atmospheric precipitation, objects such as leaves, and the like. Toulmin, in U.S. Pat. No. 3,070,643, also employs a reflector to concentrate solar rays on a point. Toulmin adjusts declination through a feedback mechanism and adjusts to diurnal movement of the sun by a motor.
Also using a parabolic mirror reflector is Bowen in U.S. Pat. No. 2,872,915, who also locates a secondary mirror as a cover over the primary mirror. Barr in U.S. Pat. No. 561,755 focuses sunlight with two mirrors on a boiler. The Brantley et al patent (U.S. Pat. No. 4,011,854) discloses a mount for continuously orienting a parabolic mirror collector dish for seasonal and diurnal solar variation of position. Specifically omitted are details of the absorber, and the patent fails to teach production of energy by a boiler or other means.
The patents above and the other patents listed below are cited to show the state of the prior art:
U.S. Pat. Nos:
787,145--Apr. 11, 1905--Brown PA1 1,220,091--Mar. 20, 1917--Goff PA1 1,993,213--Mar. 5, 1935--Gill PA1 2,460,482--Feb. 1, 1949--Abbot PA1 2,687,126--Aug. 24, 1954--Bouchet PA1 2,920,710--Jan. 12, 1960--Howard PA1 2,969,637--Jan. 31, 1961--Rowekamp PA1 3,995,429--Dec. 7, 1976--Peters. PA1 Re. 25,242--Sept. 11, 1962--Toulmin, Jr.